Aerial personnel platform with proximity sensing system

ABSTRACT

A load supporting platform, such as a workman&#39;&#39;s basket mounted on the outer end of a boom structure which is adjustable vertically and horizontally, wherein a pair of inflated resilient pneumatic tubes inflated to selected pressure are disposed in outwardly surrounding relation to the lower corner portions of the platform to contact and be deformed by objects or surfaces which are being approached by the platform, together with air pressure activated switch exposed to the pressure conditions in the pneumatic tubing and circuitry activated by the air switch to break the power circuit for the boom structure, collectively serving as a proximity sensing and protective system.

United States Patent Milner, Jr.

[451 June 20, 1972 [54] AERIAL PERSONNEL PLATFORM WITH PROXIMITY SENSING SYSTEM [72] Inventor: Edwin Earl Mllner, Jr., Williamsburg, Va.

[73] Assignee: Baker Equipment Engineering Co., Inc.,

Richmond, Va.

[22] Filed: Oct. 23, 1970 211 Appl. No.: 82,936

[52] [1.8. CI.... .....l82/19, 182/2 [5 1] Int. Cl. ..B66f 11/04 [58] Field oiSearch ..l82/l9, l8,2,63,141;49/27, 49/498 [56] References Cited UNITED STATES PATENTS 2,815,250 12/1957 Trump ..l82/2 2,221,216 11/1940 Greegor ..49/27 2,935,771 5/1960 Hatcher ..49/498 2,935,218 5/1960 Fritz ..l82/63 Primary ExaminerReinaldo P. Machado Attorney-Mason, Fenwick & Lawrence ABSTRACT A load supporting platform, such as a workmans basket mounted on the outer end of a boom structure which is adjustable vertically and horizontally, wherein a pair of inflated resilient pneumatic tubes inflated to selected pressure are disposed in outwardly surrounding relation to the lower comer portions of the platform to contact and be deformed by objects or surfaces which are being approached by the platform, together with air pressure activated switch exposed to the pressure conditions in the pneumatic tubing and circuitry activated by the air switch to break the power circuit for the boom structure, collectively serving as a proximity sensing and protective system.

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AERIAL PERSONNEL PLATFORM WITI-I PROXIMITY SENSING SYSTEM BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates in general to aerial tower type vehicles and similar structures having a workers platform or basket at the outer end of a boom structure which is adjustable vertically and horizontally, such as are employed by maintenance personnel in servicing elevated electrical systems, trees and the like and in servicing or cleaning elevated surfaces or objects such as large aircraft. More particularly, the present invention relates to a personnel basket or platform structure on the end of a pivotally mounted boom, wherein the personnel platform is provided with a proximity sensing system and bumper structure formed of inflated bumper tubes in surrounding protective relation to portions of the personnel platform connected to an air switch and circuitry to break the power circuit for the aerial boom structure upon pre-selected contact with a surface.

Service and maintenance trucks have been available for a number of years of the type generally referred to as aerial tower vehicles, wherein some type of boom structure is pivotally mounted for movement about a horizontal axis on a base or mounting structure which is journaled on the vehicle for rotation about a vertical axis, and a personnel supporting basket or platform structure is pivotally mounted on the upper end of the boom structure to support at least one worker in an elevated position. Typically, control valves for a hydraulic control system, or control devices of other known types, are provided on the workers platform for operation by the worker to permit him to control the raising and lowering and swinging movements of the boom structure and thereby enable him to move the platform to suitable elevated positions for working on high objects. Such service and maintenance trucks of the aerial tower type have been commonly used for servicing telephone and power wires, overhead traffic lights, trimming trees, installing and servicing elevated display signs or portions of such display signs, exterior decoration of buildings, painting or otherwise servicing and maintaining portions of building structures which are not readily accessible by ladders, and similar uses. Most recently, with the advent of very large commercial aircraft, such aerial tower type vehicles have come into use by maintenance personnel for servicing the aircraft. In use of such vehicles for aircraft servicing, a special care must be exercised by the operator to maintain such precise control over the position and movement of the personnel platform as to avoid impact with the skin or surface of the aircraft or any of its control surfaces or appendages in such a way as to possibly damage the aircraft. This has posed a particular problem with very large aircraft requiring boom systems which are of great axial length, particularly boom systems of the articulated type having inner and outer boom sections pivotally connected together and movable in angular relation to each other, as it is sometimes difficult for the worker to give proper attention to regulation of the controls or the operator controls in the personnel platform may lack such precise control of the boom moving apparatus as to pennit accidental movement of the personnel platform into the aircraft surface with such force as to damage the aircraft. For similar reasons, the personnel platform may accidentally come into damaging contact with buildings or other elevated objects or surfaces to which the aerial platform structure is designed to provide access. 1

An object of the present invention, therefore, is the provision of a novel mobile aerial worker's platform or basket structure such as a mobile aerial tower or the like having a proximity sensing system in the form of inflated bumper tubes disposed to protect the conventional portions of the worker's platform from contact with surfaces or objects being serviced and to automatically disable the power circuit to the devices which move the aerial platform whenever the pressure in the bumper tubes is increased to a pre-selected extent.

Another object of the present invention is the provision of a novel aerial workers platform structure mounted on a movable boom assembly and having a pair of inflated pneumatic bumpers extending around and projecting outwardly and downwardly from the lower edge portions of the platform to contact the object or surface being surfaced by the worker be fore contact by the conventional portions of the platform, and having a pressure sensitive switch arrangement operated therewith for controlling the power supply to the boom moving facilities to stop movement of the boom when the pressure in either of the bumper tubes is increased to a selected extent by contact with the object or surface being serviced.

Another object of the present invention is the provision of a novel aerial workers platform structure as described in the preceding paragraphs, wherein additional resiliently deformable, non-inflated inner bumper tubes are provided within the inflated outer bumper tubes to provide added protection in the event of failure of the inflated tubes or in the event external force totally collapses the inflated tube.

- Other objects, advantages and capabilities of the present in-' vention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a side elevation of an aerial tower truck having an articulated boom structure and a workers platform including a proximity sensing system embodying the present invention, the boom structure being shown in the collapsed or lowered position normally assumed for transportation;

FIG. 2 is a side elevation view of the workers platform with the proximity sensing system assembled thereon;

FIG. 3 is a front elevation view of the workers platform with the proximity sensing system thereon;

FIG. 4 is a top plan view of the worker's platform;

FIG. 5 is a vertical section view, to enlarged scale, throughthe proximity sensing plural bumper system and the lower front portion of the workers platform, taken along the line 55 of FIG. 3, and including diagrammatic illustration of the associated pneumatic switch circuit; and

FIG. 6 is a fragmentary horizontal section view of the bumper assembly, taken along the line 6-6 of FIG. 3.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, and particularly to FIG. 1, there is shown a mobile aerial tower type truck, generally indicated at 10, having an articulated boom structure 11, which in this embodiment comprises a first or inner boom section 12 and a second or outer boom section 13, the latter of which is of the telescoping type having a first telescoping section 13A pivotally coupled at one end, as indicated at 14 to the inner boom section 12, and including the telescopically extendable section 138 which is extendable and retractable axially within the section 13A and carries the workers platform, generally indicated at 15, on the outer end thereof. The truck, in the illustrated example, includes the drivers cab 16 and a rearwardly extending chassis portion 17 which supports a boom pedestal mechanism generally indicated at 18 capable of driving a mounting head structure 19 for the boom assembly about a vertical axis. The inner end of the first or inner boom section 12 is pivotally supported on the mounting head 19 for movement about a horizontal pivot axle or shaft indicated at 20. The inner boom section 12 is powered for vertical angular movement about the axis of the pivot shaft 20 in a conventional manner, as by the hydraulic cylinder unit 21 having a cylinder and a movable piston rod, one of which is coupled to the mounting head structure 19 and the other of which is coupled to the inner boom section 12. The outer boom section 13 is also powered angularly relative to the inner boom section 12 by conventional means, such as the hydraulic cylinder unit 22, having a cylinder which is coupled to one of the boom sections, for example the boom section 12, and a movable piston rod which is coupled to the other boom section, for example the first telescoping section 13A of the outer boom section 13. Alternatively, a drive mechanism for the boom portions at the articulation joint may be powered by a mechanism such as that disclosed in my earlier patent application Ser. No. 757,075 filed Sept. 3, 1968 or my application Ser. No. 23,834 filed Mar. 30, 1970. Also, the pedestal driving mechanism 18 for driving the pedestal and the head structure 19 about a vertical axis may be of the construction disclosed in said earlier application Ser. No. 757,075 or by other conventional pedestal driving means.

The workmans platform or basket is supported on the outer free end of the axially movable telescoping section 13B of the outer boom section 13, and in the preferred example herein illustrated is supported by a plural pivot mounting assembly 24 which includes a yoke member'25a coupled to the outer end of the axially movable telescoping section 138 by horizontal pivot shaft 25 and having a sleeve portion housing a vertical pivot shaft 26 whose ends are joumaled in a yoke type mounting bracket 26a fixed to the frame of the workers platform 15. Suitable leveling means, not shown, of a conventional construction are provided to maintain the longitudinal axes of the yoke arms 25a always in a horizontal position regardless of the angular position of the boom section 13, and suitable means such as a hydraulic cylinder unit (not shown) may be connected between the yoke member 25a and the workers platform 15 and operated by suitable hydraulic controls on the workers platform to regulate the angular position of the workers platform about the vertical axis through the vertical pivot shaft 26.

The workers platform or basket 15, the details of which are more clearly shown in FIGS. 2 through 5, includes an upwardly opening basket portion 27 of substantially rectangular configuration formed of a bottom deck 28, which in this case is formed of an open work metallic grid or grating 29 supported in conventional manner from a rectangular bottom frame 30 made up of parallel front and rear members 30A and 30B and parallel side members 30C and 30D, as well as a plurality of intermediate foreand-aft bracing members 308, each of which may be of rectangular cross-section hollow tubing as illustrated in FIG. 5. The sides of the basket portion 27 are formed of front and rear railings 31, 32 and side railings 33 and 34 each supported in a conventional manner from the bottom frame 30 and comprising for example vertical postmembers 35 and top rail members 36, which may be formed of rectangular cross-section hollow tubings similar to that used for the bottom frame 30, together with inclined strap members 37 completing the railings of the basket portion. It will be appreciated that expanded metal or other types of open work metallic material may be employed for the railing portions of the basket, or the basket may be constructed in any other suitable manner, as for example as a molded plastic basket, if desired.

A control console 38 is provided in the basket portion 27 to provide appropriate controls to be operated by the workman for operating the power means indicated diagrammatically and generally at 39 in FIG. 5 for moving the boom about the vertical pedestal axis, and the horizontal axes of the pivots and 14, and for extending and retracting the axially movable telescoping section 138, as well as for angularly positioning the basket about the pivot 26, to thereby enable the workman in the basket to regulate the position of the basket.

The proximity sensing system of the present invention,

which is carried by the workmans platform 15, is indicated generally by the reference character 40, and in the preferred embodiment comprises two generally U-shaped flexible bumper assemblies 41 and 42, the upper bumper assembly 41 extending in outwardly projecting relation from the vertical front surface of the front and side frame members 30A, C and D of the bottom frame 30 and the lower bumper assembly 42 extends downwardly from the horizontal bottom surface of the same bottom frame members. The upper bumper assembly 41 comprises an outer inflatable bladder or tube 43 of cylindrical configuration having a front leg 43A and side legs 43B and 43C within which are contained a coaxial pair of flexible bumper tubes 44 and 45 of considerably smaller diameter than the diameter of the inflatable bladder tubes 43. A U-shaped mounting strap 46 having flat side legs and a front leg corresponding substantially in length to the front and side legs of the bumper tubes 44, 45 is located within and extends along the bore or hollow interior of the inner bumper tube 45 and has spaced openings therein through which mounting bolts 47 extend. The mounting bolts have spacers 48 thereon and a larger outer diameter washer 49, held in position by a nut threaded on the mounting bolt, whereby the bolt 47 and spacer 48 extends through an accommodating opening therefor in the outer vertical wall of the front or side member of the bottom frame 30 to which it is to be secured, with the washer 49 being interposed between the outer surface of the bottom frame member and the adjacent portion of the inflatable bladder tube 43. The threaded end of the mounting bolt 47 extends through an appropriate aperture in the inner wall of the associated bottom frame member and is held in position by a nut 47a. In one example, such a mounting bolt assembly may be provided near the rear end of each of the side legs of the mounting strap 46 and two or more of such mounting bolts 47, as desired, may be spaced along the front leg of the mounting strap 46.

Similarly, as will be evident from FIG. 5, the lower flexible bumper assembly 42 includes an outer inflatable bladder tube 50 having a front leg 50A and side legs 50B and 50C, within which are located flexible bumper tubes 51 and 52 similar to v by means of a U-shaped mounting strap 53 having a front leg and a pair of rearwardly projecting side legslocated within the bore or hollow interior of the inner coaxial bumper tube 52 and supported in position by mounting bolts 47 having spacers 48, washers 49 and nuts 47A like the mounting bolt assemblies for the upper bumper assembly 41, except that in this case the mounting bolts 47 extend vertically upwardly through the bottom frame members 30A, C, and D. 1

Each of the upper bladder tubes 43 and lower bladder tubes 50 are sealed at the rearmost ends of the legs thereof which extend along or below the sides of the basket and are provided at some location along each of the bladder tubes 43 and 50 with a conventional inflation valve 53 such as a tire inflation valve for inflating the bladder tubes 43 and 50 to the desired inflation pressure by connection to a source of compressed air. Branch air hose sections 54 and 55 also connect each of the bladder tubes 43 and 50 with a Tee fitting 56 forming a manifold line between the two bladder tubes, and a hose section 57 connects the middle leg of the Tee fitting 56 to an air switch or air operated actuator 58, for example a diaphragm type switch having an adjustable spring operated by an adjustment screw to vary the setting on the air switch or actuator 58. The air switch or actuator 58 includes a plunger or movable element which is operated when the air pressure applied exceeds a selected value, to activate the switch arm of a normally closed electrical circuit control switch 59 interposed in the power line between the battery of the vehicle and the power supply terminals to the power means 39 for driving the boom and the platform to various positions. After installing the bladder tubes 43 and 50, the bladder tubes are inflated by supplying compressed air through the inflation valves 53 until the air switch 58 and circuit control switch 59 regulated thereby are activated to break the supply circuit to the power means 39. It will be appreciated that the pressure equalizes in each of the bladder tubes 43 and 50 due to the manifold formed by the branch air hose sections 54, 55 and Tee fitting 56 connected therebetween. During this inflation procedure, the air switch 58 will have been adjusted to operate on a slightly lower air pressure than the normally desired pressure value. When the bladder tubes 43 and 50 are inflated until the switches 58 and 59 are activated, the setting on the air switch or air operated actuator 58 is increased until the circuit control switch 59 returns to the normally closed configuration. Thus, when the platform and boom assembly is being operated by the workman and either of the bladder tubes 43 and 50 engage an object, the external force on either bladder will in crease the pressure on the air switch or air operated actuator 58 and if this pressure increase is of sufficient value, the switch 58 will be activated operating the circuit control switch 59 to break the supply circuits to the power means 39. When the external force deforming either of the bladder tubes is removed, the circuit returns to normal position restoring the power connection to the power means 39. The coaxial bumper tubes 44, 45 and 51, 52 provide added protection, as they resiliently cushion the impact of the worker's platform with the external object in the event of failure of the bladder tubes 43, 50 by reason of leakage, or failure of the switches 58, 59 or the associated electrical or pneumatic circuits, and also provide protection in the event the external force should totally collapse either of the bladder tubes 43, 50. Thus a proximity sensing system is provided which extends in protective relation about the portions of the workers platform which might normally come into contact with objects being serviced or approached by the platform, and wherein the inflatable bladder tubes serve as inflated bumper structures resiliently absorbing shocks upon contact with external objects and also produce increase in the air pressure within the bladder tubes due to deformation by external force to cause operation of the air switch or actuator 58 and opening of the circuit control switch 59 in the event the external force exceeds a selected value.

What is claimed is:

1. In mobile aerial platform apparatus having a movable boom structure, power means for moving the boom structure, and control means for controlling the power means; a workers platform supported on an end of the boom structure to be moved by operation of the power means to elevated positions adjacent a body to be worked upon, the workers platform having frame portions defining a structure for occupancy by the worker, a protective bumper structure supported on the frame portions of the platform and projecting outwardly therefrom in protective relation to be engaged and resiliently deformed by the body during relatively approaching movement of the body and platform, said bumper structure comprising resilient inflated pneumatic tubing inflated to selected pressure and protruding outwardly beyond the frame portions of the platform, air pressure activated switch means exposed to the air pressure conditions in said pneumatic tubing and coupled to said control means for activating the control means to disable said power means when the air pressure in said tub ing exceeds the selected value upon deformation of the tubing by contact with said body, said inflated pneumatic tubing including a first resilient pneumatic inflated tube forming a bladder protruding horizontally outwardly from said frame portions of the platform and a second pneumatic inflated tube extending vertically downwardly from frame portions of the platform about the perimeter thereof, and means pneumatically coupling said first and second tubes with said air pressure activated switch means for activating said switch means whenever the air pressure in either of said tubes exceeds said selected value.

2. Mobile aerial platform apparatus as defined in claim 1, wherein said bumper structure includes an inner resiliently deformable bumper tube disposed within said inflated pneumatic tubing and having a selected resistance to deformation to provide resilient shock absorption in the event of failure of the inflated tubing.

3. Mobile aerial platform apparatus as defined in claim 1, wherein said workers platform has a horizontal bottom and generally vertical front and side portions defining a basket structure for the worker, said inflated pneumatic tubing comprising a generally U-shaped inflated pneumatic tube of resilient material having a pair of end portions of substantially the horizontal dimensions of said platform sides extending along the platform sides and having a center portion of the horizontal dimensions of the front portion of the platform extending in outwardly protruding relation across the front to form a protective bladder about said front and side portions, said tube being inflated to selected pressure to cushion shocks upon contact with the body and being capable of being deformed by contact therewith to increase the air pressure applied to said switch means above said selected value.

4. Mobile aerial platform apparatus as defined in claim 1, including an equalizer hose communicating with said first and second tubes, said switch means including an air operated device coupled to said equalizer hose and responsive to air pressure communicated from said first and second tubes to operate said switch means to disable the power means when the air pressure exceeds said selected value.

5. ln mobile aerial platform apparatus having a movable boom structure, power means for moving the boom structure, and control means for controlling the power means; a workers platform supported on an end of the boom structure to be moved by operation of the power means to elevated positions adjacent a body to be worked upon, the worker's platform having frame portions defining a structure for occupancy by the worker, a protective bumper structure supported on the frame portions of the platform and projecting outwardly therefrom in protective relation to be engaged and resiliently deformed by the body during relatively approaching movement of the body and platfonn, said bumper structure comprising resilient inflated pneumatic tubing inflated to selected pressure and protruding outwardly beyond the frame portions of the platform, air pressure activated switch means exposed to the air pressure conditions in said pneumatic tubing and coupled to said control means for activating the control means to disable said power means when the air pressure in said tubing exceeds the selected value upon deformation of the tubing by contact with said body, said workers platform having a horizontal bottom and generally vertical front and side portions defining a basket structure for the worker, said inflated pneumatic tubing comprising a first U-shaped pneumatic tube forming a protective bladder extending across the front and along the sides of said platform in outwardly protruding relation in'a horizontal direction, and a second U-shaped pneumatic tube extending downwardly from the bottom of said platform at the juncture of the bottom with said front and side portions to fonn a downwardly extending protective bladder, each of said first and second tubes being inflated to a selected pressure to cushion shocks from contact with the body and being capable of being deformed by contact with the body to increase the air pressure applied to said switch means above said selected value.

6. Mobile aerial platform apparatus as defined in claim 5, including an equalizer hose communicating with said first and second tubes, said switch means including an air operated device coupled to said equalizer hose and responsive to air pressure communicated from said first and second tubes to operate said switch means to disable the power means when the air pressure exceeds said selected value.

7. In mobile aerial platform apparatus having a movable boom structure, power means for moving the boom structure, and control means for controlling the power means; a platform supported on the end of the boom structure for supporting a load and to be moved by operation of the power means to elevated positions adjacent a stationary body to be approached by the platform, the platform having frame portions defining a structure for supporting the load, a protective bumper structure supported on the frame portions of the platform and projecting outwardly therefrom in protective relation to be engaged and resiliently deformed by the body during relative approaching movement of the body and platform, said bumper structure comprising resilient inflated pneumatic tubing inflated to selected pressure and protruding outwardly beyond the frame portions of the platform, air pressure activated switch means exposed to the air pressure conditions in said pneumatic tubing and coupled to said control means for activating the control means to disable said power means when the air pressure in said tubing exceeds the selected value upon deformation of the tubing by contact with said body, said inflated pneumatic tubing including a first resilient pneumatic inflated tube forming a bladder protruding horizontally outwardly from said frame portions of the platform and a second pneumatic inflated tube extending vertically downwardly from frame portions of the platform about the perimeter thereof, and means pneumatically coupling said first and second tubes with said air pressure activated switch means for activating said switch means whenever the air pressure in either of said tubes exceeds said selected value.

8. Mobile aerial platform apparatus as defined in claim 7, wherein said bumper structure includes an inner resiliently deformable bumper tube disposed within said inflated pneumatic tubing and having a selected resistance to deformation to provide resilient shock absorption in the event of failure of the inflated tubing.

9. Mobile aerial platform apparatus as defined in claim 7,

wherein said platform has a substantially rectangular bottom portion, said inflated pneumatic tubing comprising a generally U-shaped inflated pneumatic tube of resilient material having a pair of end portions of substantially the horizontal dimensions of the sides of the lower portion of said platform extending along the platform sides and having a center portion of the horizontal dimensions of the front portion of the platform extending in outwardly protruding relation across the front to form a protective bladder about said front and side portions, said tube being inflated to selected pressure to cushion shocks upon contact with the body and being capable of being deformed by contact therewith to increase the air pressure ap plied to said switch means aaove said selected value.

10. Mobile aerial apparatus as defined in claim 7, including an equalizer hose communicating with said first and second tubes, said switch means including an air operated device coupled to said equalizer hose and responsive to air pressure communicated from said first and second tubes to operate said switch means to disable the power means when the air pressure exceeds said selected value. 

1. In mobile aerial platform apparatus having a movable boom structure, power means for moving the boom structure, and control means for controlling the power means; a worker''s platform supported on an end of the boom structure to be moved by operation of the power means to elevated positions adjacent a body to be worked upon, the worker''s platform having frame portions defining a structure for occupancy by the worker, a protective bumper structure supported on the frame portions of the platform and projecting outwardly therefrom in protective relation to be engaged and resiliently deformed by the body during relatively approaching movement of the body and platform, said bumper structure comprising resilient inflated pneumatic tubing inflated to selected pressure and protruding outwardly beyond the frame portions of the platform, air pressure activated switch means exposed to the air pressure conditions in said pneumatic tubing and coupled to said control means for activating the control means to disable said power means when the air pressure in said tubing exceeds the selected value upon deformation of the tubing by contact with said body, said inflated pneumatic tubing including a first resilient pneumatic inflated tube forming a bladder protruding horizontally outwardly from said frame portions of the platform and a second pneumatic inflated tube extending vertically downwardly from frame portions of the platform about the perimeter thereof, and means pneumatically coupling said first and second tubes with said air pressure activated switch means for activating said switch means whenever the air pressure in either of said tubes exceeds said selected value.
 2. Mobile aerial platform apparatus as defined in claim 1, wherein said bumper structure includes an inner resiliently deformable bumper tube disposed within said inflated pneumatic tubing and having a selected resistance to deformation to provide resilient shock absorption in the event of failure of the inflated tubing.
 3. Mobile aerial platform apparatus as defined in claim 1, wherein said worker''s platform has a horizontal bottom and generally vertical front and side portions defining a basket structure for the worker, said inflated pneumatic tubing comprising a generally U-shaped inflated pneumatic tube of resilient material having a pair of end portions of substantially the horizontal dimensions of said platform sides extending along the platform sides and having a center portion of the horizontal dimensions of the front portion of the platform extending in outwardly protruding relation across the front to form a protective bladder about said front and side portions, said tube being inflated to selected pressure to cushion shocks upon contact with the body and being capable of being deformed by contact therewith to increase the air pressure applied to said switch means above said selected value.
 4. Mobile aerial platform apparatus as defined in claim 1, including an equalizer hose communicating with said first and second tubes, said switch means including an air operated device coupled to said equalizer hose and responsive to air pressure communicated from said first and second tubes to operate said switch means to disable the power means when the air pressure exceeds said selected value.
 5. In mobile aerial platform apparatus having a movable boom structure, power means for moving the boom structure, and control means for controlling the power means; a worker''s platform supported on an end of the boom structure to be moved by operation of the power means to elevated positions adjacent a body to be worked upon, the worker''s platform having frame portions defining a structure for occupancy by the worker, a protective bumper structure supported on the frame portions of the platform and projecting outwardly therefrom in protective relation to be engaged and resiliently deformed by thE body during relatively approaching movement of the body and platform, said bumper structure comprising resilient inflated pneumatic tubing inflated to selected pressure and protruding outwardly beyond the frame portions of the platform, air pressure activated switch means exposed to the air pressure conditions in said pneumatic tubing and coupled to said control means for activating the control means to disable said power means when the air pressure in said tubing exceeds the selected value upon deformation of the tubing by contact with said body, said worker''s platform having a horizontal bottom and generally vertical front and side portions defining a basket structure for the worker, said inflated pneumatic tubing comprising a first U-shaped pneumatic tube forming a protective bladder extending across the front and along the sides of said platform in outwardly protruding relation in a horizontal direction, and a second U-shaped pneumatic tube extending downwardly from the bottom of said platform at the juncture of the bottom with said front and side portions to form a downwardly extending protective bladder, each of said first and second tubes being inflated to a selected pressure to cushion shocks from contact with the body and being capable of being deformed by contact with the body to increase the air pressure applied to said switch means above said selected value.
 6. Mobile aerial platform apparatus as defined in claim 5, including an equalizer hose communicating with said first and second tubes, said switch means including an air operated device coupled to said equalizer hose and responsive to air pressure communicated from said first and second tubes to operate said switch means to disable the power means when the air pressure exceeds said selected value.
 7. In mobile aerial platform apparatus having a movable boom structure, power means for moving the boom structure, and control means for controlling the power means; a platform supported on the end of the boom structure for supporting a load and to be moved by operation of the power means to elevated positions adjacent a stationary body to be approached by the platform, the platform having frame portions defining a structure for supporting the load, a protective bumper structure supported on the frame portions of the platform and projecting outwardly therefrom in protective relation to be engaged and resiliently deformed by the body during relative approaching movement of the body and platform, said bumper structure comprising resilient inflated pneumatic tubing inflated to selected pressure and protruding outwardly beyond the frame portions of the platform, air pressure activated switch means exposed to the air pressure conditions in said pneumatic tubing and coupled to said control means for activating the control means to disable said power means when the air pressure in said tubing exceeds the selected value upon deformation of the tubing by contact with said body, said inflated pneumatic tubing including a first resilient pneumatic inflated tube forming a bladder protruding horizontally outwardly from said frame portions of the platform and a second pneumatic inflated tube extending vertically downwardly from frame portions of the platform about the perimeter thereof, and means pneumatically coupling said first and second tubes with said air pressure activated switch means for activating said switch means whenever the air pressure in either of said tubes exceeds said selected value.
 8. Mobile aerial platform apparatus as defined in claim 7, wherein said bumper structure includes an inner resiliently deformable bumper tube disposed within said inflated pneumatic tubing and having a selected resistance to deformation to provide resilient shock absorption in the event of failure of the inflated tubing.
 9. Mobile aerial platform apparatus as defined in claim 7, wherein said platform has a substantially rectangular bottom portion, said inflated pneumatic tubing comprising a generally U-shaped iNflated pneumatic tube of resilient material having a pair of end portions of substantially the horizontal dimensions of the sides of the lower portion of said platform extending along the platform sides and having a center portion of the horizontal dimensions of the front portion of the platform extending in outwardly protruding relation across the front to form a protective bladder about said front and side portions, said tube being inflated to selected pressure to cushion shocks upon contact with the body and being capable of being deformed by contact therewith to increase the air pressure applied to said switch means above said selected value.
 10. Mobile aerial apparatus as defined in claim 7, including an equalizer hose communicating with said first and second tubes, said switch means including an air operated device coupled to said equalizer hose and responsive to air pressure communicated from said first and second tubes to operate said switch means to disable the power means when the air pressure exceeds said selected value. 